Power merge-synchronous

ABSTRACT

In a unit carrier system in which a plurality of cars are driven over a trackway, a merge assisting device for interleaving on an outgoing track cars approaching a merge on a plurality of different incoming tracks. In its preferred form, this device comprises chain-mounted dogs which cooperate with cams mounted on the sides of the cars to accelerate the cars from their incoming speeds to outgoing speeds sufficiently greater than their incoming speeds so that the cars may be interleaved at the merge without danger of collision.

1 Dec. 17, 1974 United States Patent 1 Bradbury POWER MERGE-SYNCHRONOUSPrimary Examiner-M. Henson Wood, Jr.

Assistant Examiner-Richard A. Bertsch 1 B G. B db Ch' C l'f. [75]Inventor emard m my 100 an Attorney, Agent, or F1rn1Sughrue, Rothwell,Mum,

Zinn & Macpeak [73] Assignee: Rexnord Inc., Milwaukee, Wis.

Nov. 19, 1973 [22] Filed:

[57] ABSTRACT In a unit carrier system in which a plurality of cars aredriven over a trackway, a merge assisting device for interleaving on anoutgoing track cars approaching a merge on a plurality of differentincoming tracks. in its preferred form, this device comprises chain-Appl. No.: 417,322

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mounted dogs which cooperate with cams mounted on the sides of the carsto accelerate the cars from their incoming speeds to outgoing speedssufficiently greater than their incoming speeds so that the cars S T N mm mm QT mA me e D E n N U m 5 104/172 R may be interleaved at the mergewithout danger of 104/96 collision. 104/130 3,044,415 7/1962 3 196 8047/1965 Harrison 3,477,388 11/1969 Klamp 45 Claims, 9 Drawing FiguresPATENTED HEB] H914 SHEET 2 BF 2 POWER MERGE-SYNCHRONOUS FIELD OF THEINVENTION This invention relates generally to power merges in a unitcarrier system and, more specifically, to power merges suitable for usewith a unit carrier system such as is disclosed in commonly assignedU.S. Pats. Nos. 3,621,790, 3,626,859, and 3,650,216.

BACKGROUND OF THE INVENTION Commonly assigned U.S. Pat. No. 3,626,859discloses an idle-car storage and dispensing system which may also beused as a merging system, the cars on the subsidiary of two merginglines being handled in the same way as the sidelined, idle cars are inthat patent. In such a system, a car on the subsidiary line may bestopped just short of the merge by a dynamic stop such as is disclosedin commonly assigned U.S. application Ser. No. 309,026, filed Nov. 24,1972, and later abandoned in favor of continuation application Ser. No.463,716, filed Apr. 24, 1974, if appropriate photocells or other sensorssuch as are disclosed in U.S. Pat. No. 3,626,859 detect an impendingcollision if the car is allowed to proceed immediately on to the mainline. Once the car is stopped, it remains in the stopped position untila clear window is sensed on the main line. When such a window is sensed,the dynamic stop is retracted, and the friction-powered car drive thenpropels the car out on to the main line, where it gradually attains thesame velocity as the other cars already on that line. All this isexplained more fully in U.S. Pat. No. 3,626,859, and the apparatusdisclosed therein is satisfactory for many situations.

However, the accelerational ability of many unit carriers is inherentlyrather limited, and configurations such as that disclosed in U.S. Pat.No. 3,626,859 accordingly requires a rather long clear window in thestream of traffic on the main line in order to allow the stopped car onthe subsidiary line to move out on to the main line without danger of arear-end collision. If the main line is heavily trafficked, thisrequirement can easily result in a highly undesirable backup of the carson the subsidiary line.

As a solution to this problem, I developed the accelerator mergedisclosed in commonly assigned U.S. patent application Ser. No. 315,059,filed Dec. I4, 1972. In the preferred embodiment of this device, theclear window required in the stream of traffic on the main line in orderto allow a stopped car on the subsidiary line to move out on to the mainline without danger of a rear-end collision is considerably shortened.This is accomplished by assisting the acceleration of the car with anexternal power source which acts on a cam mounted on the side of thecar. The cam is engaged by a dog mounted on a chain which parallels thefixed path of the car so that the dog remains in engagement with the camfor a considerable portion of the time it is accelerating. The chain is,in turn. powered by any appropriate means, as, for instance, a hydraulicmotor.

However, this device is most suitable for use in a system where the carsare brought to a complete stop on the subsidiary line before longaccelerated out on to the main line, and it still requires that a clearwindow be found in the stream of traffic on the main line, whichrequirement can still result in an undesirable backup of the cars on thesubsidiary line if the main line is heavily enough trafficked.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is aplan view of a merge having two incoming lines and employing anembodiment of the present invention. Some superstructure shown in theother figures is omitted for the sake of clarity.

FIG. 2 is a view taken along the lines 22 in FIG. 1,

but omitting some background detail.

FIG. 3 is a view taken along the lines 33 in FIG. 1.

FIG. 4 is a view taken along the lines 44 in FIG. 1, but omitting thebackground.

FIG. 5 is a greatly enlarged view of a detail of FIG. 1.

FIG. 6 is a side view of the plan view shown in FIG. 5, but omitting thesprocket.

FIG. 7. is a view taken along the lines 77 in FIG. 6.

FIG. 8 is a view taken along the lines 88 in FIG. 6, showing a camengaged by a dog.

FIG. 9 is a view taken in the same place as FIG. 8, but showing the camforcing the dog out of the way.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT To illustrate the presentinvention, a merge having two incoming lines will be described indetail. It will be understood, however, that the principal of thepresent invention is equally applicable to merges having more than twoincoming lines.

FIG. 1 shows a merge of a line 10 with a line 12 in the trackway of atrack-guided unit carrier system. As shown by the arrows, the cars 14 onboth lines move from left to right. The cars 14 have two cam followers16, one mounted on either side thereof. The cam followers 16 may be usedin unloading the cars 14 while in motion in the manner set forth incommonly assigned U.S. Pat. No. 3,613,916, and they may also be used toaccelerate the cars 14 from the velocities at which they approach themerge to a velocity permitting them to be interleaved at the mergewithout danger of collision. As will be obvious from what follows, meansmust be provided for driving the cars 14 on the outgoing track at thespeed to which they are brought by the merge device described andclaimed herein, but. as these means form no part of the presentinvention, they will not be described herein.

Mounted adjacent to each of the incoming tracks are controlled-pathway,propelling devices, designated generally by the numeral 18, each ofwhich comprises two parallel chains 20, 22 and a plurality of doublesprockets 24. Each of the pairs of parallel chains 20, 22

carries between the two chains a plurality of dogs 26 (shown in detailin FIGS. -9) and a plurality of supporting plates 28 which are carriedby the chains 20, 22 at much closer intervals than the dogs 26 and serveto support the upper chain 20. The plates 28 must either (I) beconstructed of sufficiently flexible material to permit them to flex asthey are passed around the double sprockets 24, (2) be mounted on thechains 20, 22 with provisions for lost motion in the mounting permittingthem to turn the corners without bending, or (3) be connected to onelink only on each chain 20, 22.

The controlled-pathway, propelling devices 18 are positioned so that thedogs 26 which they carry will engage the upstream side of the camfollowers 16 on the adjacent side of the cars 14 as they approach themerge and remain in engagement with them until the cars have at leastreached the merge. The dogs 26 are preferably constructed in the mannershown in FIGS. 5-9 in order (I) to absorb some of the shock of impactwhen the dog 26 comes into contact with a cam follower 16 and (2) topermit the operative portion of the dog 26 to pivot out of the way inthe event that the dog and a cam follower reach the same point at thesame time. As shown, the preferred embodiment of the dog 26 comprises anengaging block 50, two pivotable pull arms 52, two pull sleeves 54, andfour compression springs 56 mounted on two U-bolts 58, the formerserving to bias the pull arms 52 against the pull sleeve 54. As bestseen in FIGS. 6 and 8, the engaging block 50 is positioned to bearagainst the upstream surface of the cam follower 16 when the dog 26overtakes the cam follower 16 in the ordinary course of events. Sincethe dog 26 would then be moving much faster than the cam follower 16,the overtaking of the cam follower 16 by the dog 26 causes aconsiderable impact, part of the force of which is taken up by thecompression of the compression springs 56 between inner spring seats inthe pull sleeves 54 and the upstream surfaces of the saddles 60. Duringthis process, the pull arms 52 separate from the pull sleeves 54 and thesaddles 60 slide along the links of the chains 20, 22. The springs 56are mounted on the U-bolts 58 which wrap around mating surfaces of thepull arms 52, transmitting the impact from the cam follower 16 throughthe dogs 26 to the chains 20, 22.

To permit the engaging block 50 to pivot out of the way in case it and acam follower 16 reach the same point at the same time, the pull arms 52are adapted to pivot in the bases of the U-bolts 58. As may best beunderstood by comparing FIGS. 8 and 9, the compression springs 56normally pull the flat, downstream surfaces of the pull arms 52 againstthe flat, upstream surfaces of the pull sleeves 54, as depicted in FIG.8, but if the engaging block 50 and the cam follower 16 begin to bindlaterally, the cam follower forces the pull arms 52 to pivot aroundtheir outboard, downstream corners, permitting the dog 26 to pass by thecam follower 16 without engaging it. In that event, the car 14 is pickedup by the next dog 26, and the controlled-pathway,-

propelling devices 18 must accordingly be long enough so that a car 14can just miss one dog 26 in this fashion, and yet be picked up andaccelerated by the next succeeding dog 26 before it reaches the merge.

The controlled-pathway, propelling devices 18 are driven by motor 30 ata speed at least equal to the fastest speed at which the cars 14 enterthe merge times the number of incoming tracks. In the simplest case,where there are only two incoming tracks and all cars on both incomingtracks are moving at the same speed, the controlled-pathway, propellingdevices 18 are driven at a speed of at least twice that of the incomingcars.

The motor 30 drives a chain 32 which in turn drives both pairs ofparallel chains 20, 22, as seen in the upper right-hand of FIG. 1 and inFIG. 2. The chain 32 also serves the essential function of synchronizingthe two controlled-pathway, propelling devices 18 so that the cars 14approaching the merge on the tracks 10 and 12 reach it alternately andat intervals permitting them to interleave without colliding with oneanother. In general, this is accomplished by spacing the dogs so thatthe last car 14 reaching the merge on one incoming track before a car 14reaches the merge on another incoming track is followed by an intervalslightly in excess of the length of the longest car 14. The requirementthat the interval be slightly in excess of the length of the longest carcomes from the fact that the cars on different tracks are non-parallelas they merge, presenting to one another, not their length from front toback, but a length depending on the abruptness of the merge butapproximating the distance from one front comer to the opposite rearcorner.

Of course, the chain 32 and the dogs 26 must also be arranged so thatthe cars from the various incoming tracks reach the merge alternately.The alternation may be one-to-one or it may be at any integral ratio.The former type of alteration is useful where the incoming trackways areapproximately equally heavily trafficked by cars moving at approximatelythe same speed, and the more general type of alternation is useful wherecertain of the trackways are consistently more heavily trafficked thanothers and/or the speed of the incoming cars on certain of the trackwaysis consistently greater than the speed on others.

In the embodiment shown in the drawing, a plurality of dogs 26 arecarried by each controlled-pathway, propelling device 18, the dogs 26being driven continuously in one direction and being spaced by adistance slightly in excess of twice the length of the longest of thecars 14 so as to leave a gap between two successive cars on one linesufficient for a car from the other line. In this embodiment, thedistance upstream of the merge to which the controlled-pathway,propelling device 18 extends need only be sufficient so that an incomingcar approaching the device just after a dog 26 carried by the device 18has passed will be brought into synchronization by the following dogbefore the car has reached the merge.

Alternatively, the controlled-pathway, propelling devices 28 can carry asingle dog 26, in which case the distance upstream of the merge to whichthe device must extend has to be sufficient so that an incoming careapproaching the device just after the dog has passed will be broughtinto synchronization by the dog on its next pass before the car hasreached the merge. This type of construction, more fully described in mycopending, commonly assigned application Ser. No. 315,059, filed Dec.14, 1972, and later abandoned in favor of continuation application Ser.No. 463,716, filed Apr. 24, 1974 is most useful when a linearreciprocating device, such as a hydraulic cylinder, is used instead ofthe device shown. Such a device may be used either directly or inconnection with a chain and sprocket assembly which is driven first inone direction, then in the other, so as to recock the dog for successivecars. In either case, it is necessary to mount the dog 26 ratchetfashion, so that it will not engage the cam fol lower 16 while beingrecocked, but will do so on its driving stroke.

To give the chains 20, 22 the strength required to transmit the powerneeded to accelerate the cars 14 by the required amount within areasonable distance, it is necessary that they be quite heavy if thecars have appreciable mass, as they do in the uses contemplated by myassignee. In order to support and guide the chains 20, 22, I accordinglyuse a quite elaborate structure illustrated in FIGS. 3 and 4. As may beseen therein, the chains 20, 22 are connected by the previouslymentioned plates 28, which are spaced at frequent intervals. The plates28 support the upper chain 20 on the lower chain 22. At least while onthe part of its path nearer to the cars, and, if the chain is heavyenough, during part or all of the rest of its path as well, the lowerchain 22 is in turn supported on the horizontal wear strip 31 mounted onthe structural member 32. The rollers of the chains 20, 22 are alsoguided laterally during at least the time during which they are adjacentto the cars by lateral wear strips 34, 36, which are mounted onstructural members 32 and 38, respectively.

Since the dogs 26 travel at a much greater speed than the cars 14 asthey enter the device, some means for ab sorbing the impact of the oneon the other is required. The previously described compression springs56 perform part of this function. However, in practice it has been founddesirable to provide additional impactabsorbing means as well. Suchmeans could take various forms as, for instance, a spring mounting ofthe cam followers 16 on the sides of the cars 14. However, I havedevised a particularly satisfactory way of absorbing the impact andallowing acceleration to be transferred to the cars relatively graduallyin which the absorbing means are a part of the drive means for thecontrolled-pathway, propelling device rather than on the carsthemselves. As shown in FIG. 2, the double drive sprockets 24a aremounted on torsional springs 40 which normally transmit torque to thedouble sprockets 24a in the manner of a cylindrical shaft, but whichabsorb the impact of the cars 14 on the dogs 26 by uncurling slightly.In order to handle bumper-to-bumper traftic, the torsional springs 40must be strong enough so that the impact of successive cars can beabsorbed while a dog 26 is still in contact with and driving a previouscar 14. In order to improve the resistance of the torsional springs 40to axial flexing (i.e., bending of the axis), they may be mounted onshafts (not shown) such that the inner peripheries of the springs slideagainst the outer peripheries of the shafts as the springs curl anduncurl. If this expedient is used, however, it must be remembered thatthe torque from the motor 30 is transmitted through the torsionalsprings and not through the shafts.

Caveat While the present invention has been illustrated by a detaileddescription of a preferred embodiment thereof, it will be obvious tothose skilled in the art that various changes in form and detail can bemade therein without departing from the true scope of the invention. Forinstance, the two parallel accelerator chains are not a necessaryfeature of the present invention. While it has been found that carryingthe dogs between two parallel chains gives added strength and stabilitytothe system, obviously the dogs could be carried on a single chain,particularly where the car and its contents were not heavy. Similarly,the dogs would not have to be carried on a chain or chains at all, butcould be carried by any suitable controlled-pathway, propelling device,and the cam followers which engage the dogs need not be mounted on thesides of the car. They can as well be mounted on the top or bottomthereof, provided that the pathway of the dog is designed accordingly,or they could be dispensed with altogether and the dogs could engagesome appropriate part of the cars themselves as, for instance, the rearend. Likewise, the synchronization of the controlled-pathway, propellingdevices could be accomplished by electronic or any other appropriatemeans, rather than by means such as chain 32. Thus, my invention must bemeasured by the claims appended hereto and not by the foregoingpreferred embodiment.

What is claimed is:

1. In a unit carrier system in which a plurality of cars are driven overa trackway having merges therein, a merge assisting device forinterleaving on an outgoing track cars approaching a merge on aplurality of different incoming tracks without stopping said cars priorto the merge, said merge assisting device comprising:

a controlled-pathway, propelling device mounted adjacent to each of saidincoming tracks; at least one dog carried by each of saidcontrolledpathway, propelling devices and positioned to engage anincoming car on the adjacent one of said incoming tracks and to remainin engagement with said car until it has reached an exit speed at leastequal to the speed of the fastest of said incoming cars times the numberof said incoming tracks;

means for driving said controlled-pathway, propelling devices at saidexit speed; and

means for synchronizing said controlled-pathway,

propelling devices so that said cars reach said merge at intervals atleast slightly in excess of the length of the longest of said cars,whereby said cars may be interleaved on said outgoing track withoutdanger of collision with one another.

2. A merge assisting device as claimed in claim 1 wherein at least oneof said controlled-pathway, propelling devices comprises:

a chain and a plurality of sprockets for guiding said chain andimparting motion thereto.

3. A merge assisting device as claimed in claim 2 wherein said sprocketsare driven in only one direction.

4. A merge assisting device as claimed in claim 2 wherein said sprocketsare driven first in one direction, then in the other, whereby said dogis recocked for successive cars.

5. A merge assisting device as claimed in claim 2 wherein said dog iscarried between two parallel chains.

6. A merge assisting device as claimed in claim 5 wherein saidcontrolled-pathway, propelling device further comprises guide means forsupporting said parallel chains and preventing deviation thereof fromtheir prescribed pathway during that portion of their prescribed pathwayduring which said dog is in position to engage said cars.

7. A merge assisting device as claimed in claim 2 wherein said means fordriving said controlledpathway, propelling device includes torsionalsprings which normally transmit torque to said sprockets in the mannerof a cylindrical shaft, but which absorb the impact of said cars on saiddog by curling or uncurling slightly.

8. A merge assisting device as claimed in claim I and further comprisingmeans for absorbing the impact of said cars on said dogs.

9. A merge assisting device as claimed in claim 1 wherein saidcontrolled-pathway, propelling device extends from upstream of saidmerge at least to said merge.

10. A merge assisting device as claimed in claim I wherein said dogcomprises:

1. a pull sleeve mounted on said controlled-pathway,

propelling device;

2. an engaging block positioned to engage an incoming car on theadjacent one of said incoming tracks; and

3. yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid cars on said engaging block.

11. A merge assisting device as claimed in claim 10 wherein saidyielding means comprises a spring.

12. A merge assisting device as claimed in claim 10 wherein saidyielding means comprises:

1. a bolt connected to said engaging block and slidable in said pullsleeve;

2. a spring co-axially disposed about said bolt; and

3. butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said cars on said engaging block.

13. A merge assisting device as claimed in claim 10 wherein saidengaging block is pivotably mounted on said yielding means, saidengaging block being pivotable from a position in which it can engage anincoming car on the adjacent one of said incoming tracks to a positionin which said engaging block cannot engage incoming cars on the adjacentone of said incoming tracks.

14. A merge assisting device as claimed in claim 1 wherein said dog ispivotably mounted on said controlled-pathway, propelling device, saiddog being pivotable from a position in which it can engage an incomingcar on the adjacent one of said incoming tracks to a position in whichsaid engaging block cannot engage incoming cars on the adjacent one ofsaid incoming tracks.

15. A dog adapted to be mounted on a controlledpathway, propellingdevice and to impart momentum to objects moving on a controlled pathadjacent to said controlled-pathway, propelling device, said dogcomprising:

l. a pull sleeve mounted on said controlled-pathway,

propelling device;

2. an engaging block positioned to engage one of said objects; and

3. yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid object on said engaging block.

16. A dog as claimed in claim wherein said yielding means comprises aspring.

17. A dog as claimed in claim 15 wherein said yielding means comprises:

1. a bolt connected to said engaging block and slidable in said pullsleeve;

2. a spring co-axially disposed about said bolt; and

3. butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said object on said engaging block.

18. A dog as claimed in claim 15 wherein said engaging block ispivotably mounted on said yielding means, said engaging block beingpivotable from a position in which it can engage an incoming object to aposition in which said engaging block cannot engage an incoming object.

19. In a unit carrier system in which a plurality of cars are drivenover a trackway having merges therein, a merge assisting device forinterleaving on an outgoing track cars approaching a merge on aplurality of different incoming tracks, said merge assisting devicecomprising:

a. a controlled-pathway, propelling device mounted adjacent to each ofsaid incoming tracks, the distance upstream of said merge to which saidcontrolled-pathway, reciprocating device extends being sufficient sothat an incoming car approaching said device just after a dog (to berecited hereinafter) carried by said device has passed will be broughtinto synchronization by the following dog before said car has reachedsaid merge; b. a plurality of dogs carried by at least one of saidcontrolled-pathway, propelling devices, said dogs being spaced by adistance slightly in excess of the longest of said cars times the numberof said incoming trackways and being positioned to engage an incomingcar on the adjacent one of said incoming tracks and to remain inengagement with said car until it has reached an exit speed at leastequal to the speed of the fastest of said incoming cars times the numberof said incoming tracks; c. at least one dog i. carried by each of saidcontrolled-pathway, propelling devices other than said at least one ofsaid controlled-pathway, propelling devices and ii. positioned to engagean incoming car on the adjacent one of said incoming tracks and toremain in engagement with said car until it has reached an exit speed atleast equal to the speed of the fastest of said incoming cars times thenumber of said incoming tracks;

(1. means for driving said controlled-pathway, propelling devices atsaid exit speed; and

e. means for synchronizing said controlled-pathway, propelling devicesso that said cars reach said merge at intervals at least slightly inexcess of the length of the longest of said cars, whereby said cars maybe interleaved on said outgoing track without danger of collision withone another.

20. A merge assisting device as claimed in claim 19 wherein said one ofsaid controlled-pathway, propelling devices comprises:

a chain and a plurality of sprockets for guiding said chain andimparting motion thereto.

21. A merge assisting device as claimed in claim wherein said sprocketsare driven in only one direction.

22. A merge assisting device as claimed in claim 20 wherein saidsprockets are driven first in one direction, then in the other, wherebysaid dog is recocked for successive cars.

23. A merge assisting device as claimed in claim 20 wherein said dog iscarried between two parallel chains.

24. A merge assisting device as claimed in claim 23 wherein saidcontrolled-pathway, propelling device fur ther comprises guide means forsupporting said parallel chains and preventing deviation thereof fromtheir prescribed pathway during that portion of their prescribed pathwayduring which said dog is in position to engage said cars.

25. A merge assisting device as claimed in claim 20 wherein said meansfor driving said controlledpathway, propelling device includes torsionalsprings which normally transmit torque to said sprockets in the mannerof a cylindrical shaft, but which absorb the impact of said cars on saiddog by curling or .uncurling slightly.

26. A merge assisting device as claimed in claim 19 and furthercomprising means for absorbing the impact of said cars on said dogs.

27. A merge assisting device as claimed in claim 19 wherein said one ofsaid controlled-pathway, propelling device extends from upstream of saidmerge at least to said merge.

28. A merge assisting device as claimed in claim 19 wherein said dogcomprises:

1. a pull sleeve mounted on said controlled-pathway,

propelling device;

2. an engaging block positioned to engage an incoming car on theadjacent one of said incoming tracks; and

3. yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid cars on said engaging block.

29. A merge assisting device as claimed in claim 28 wherein saidyielding means comprises a spring.

30. A merge assisting device as claimed in claim 28 wherein saidyielding means comprises:

1. a bolt connected to said engaging block and slidable in said sleeve;

2. a spring co-axially disposed about said bolt; and

3. butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said cars on said engaging block.

31. A merge assisting device as claimed in claim 28 wherein saidengaging block is pivotably mounted on said yielding means, saidengaging block being pivotable from a position in which it can engage anincoming car on the adjacent one of said incoming tracks to a positionin which said engaging block cannot engage incoming cars on the adjacentone of said incoming tracks.

32. A merge assisting device as claimed in claim 19 wherein said dog ispivotably mounted on said controlled-pathway, propelling device, saiddog being pivotable from a position in which it can engage an incomingcar on the adjacent one of said incoming tracks to a position in whichsaid engaging block cannot engage incoming cars on the adjacent one ofsaid incoming tracks.

33. In a unit carrier system in which a plurality of cars are drivenover a trackway having merges therein, a merge assisting device forinterleaving on an outgoing track cars approaching a merge on aplurality of different incoming tracks, said merge assisting devicecomprising:

a. a first controlled-pathway, propelling device mounted adjacent to afirst one of said incoming tracks, the distance upstream of said mergeto which said first controlled-pathway, propelling device extends beingsufficient so that an incoming car approaching said firstcontrolled-pathway, pro pelling device just after a dog (to be recitedhereinafter) carried by said device has passed will be brought intosynchronization by said dog on its next pass before said car has reachedsaid merge,

b. a single dog i. carried by said first controlled-pathway, propellingdevice and ii. positioned to engage an incoming car on said first one ofsaid incoming tracks and to remain in engagement with said car until ithas reached an exit speed at least equal to the speed of the fastest ofsaid incoming cars times the number of said incoming track;

c. an additional controlled-pathway, propelling device mounted adjacentto the other or each of the other additional incoming tracks;

d. at least one dog i. carried by the other or each of the otheradditional incoming tracks and ii. positioned to engage an incoming caron the adjacent one of said incoming tracks and to remain in engagementwith said car until it has reached an exit speed at least equal to thespeed of the fastest of said incoming cars times the number of saidincoming tracks;

e. means for driving said controlled-pathway, propelling devices at saidexit speed; and

f. means for synchronizing said controlled-pathway, propelling devicesso that said cars reach said merge at intervals at least slightly inexcess of the length of the longest of said cars,

whereby said cars may be interleaved on said outgoing track withoutdanger of collision with one another.

34. A merge assisting device as claimed in claim 33 wherein said firstcontrolled-pathway, propelling devices comprises:

a chain and a plurality of sprockets for guiding said chain andimparting motion thereto.

35. A merge assisting device as claimed in claim 34 wherein saidsprockets are driven in only one direction.

36. A merge assisting device as claimed in claim 34 wherein saidsprockets are driven first in one direction, then in the other, wherebysaid single dog is recocked for successive cars.

37. A merge assisting device as claimed in claim 34 wherein said singledog is carried between two parallel chains.

38. A merge assisting device as claimed in claim 37 wherein said firstcontrolled-pathway, propelling device further comprises guide means forsupporting said parallel chains and preventing deviation thereof fromtheir prescribed pathway during the portion of their prescribed pathwayduring which said dog is in position to engage said cars.

39. A merge assisting device as claimed in claim 34 wherein said meansfor driving said first controlledpathway, propelling device includestorsional springs which normally transmit torque to said sprockets inthe manner of a cylindrical shaft, but which absorb the impact of saidcars on said single dog by curling or uncurling slightly.

40. A merge assisting device as claimed in claim 33 and furthercomprising means for absorbing the impact of said cars on said singledog.

41. A merge assisting device as claimed in claim 33 wherein said firstcontrolled-pathway, propelling device extends from upstream of saidmerge at least to said merge.

42. A merge assisting device as claimed in claim 33 wherein said singledog comprises:

1. a pull sleeve mounted on said controlled-pathway,

propelling device;

2. an engaging block positioned to engage an incoming car on theadjacent one of said incoming tracks;

and

3. yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid cars on said engaging block.

43. A merge assisting device as claimed in claim 42 wherein saidyielding means comprises a spring.

44. A merge assisting device as claimed in claim 42 wherein saidyielding means comprises:

1. a bolt connected to said engaging block and slid able in said sleeve;

2. a spring co-axially disposed about said bolt; and

3. butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said cars on said engaging block.

45. A merge assisting device as claimed in claim 33 wherein saidengaging block is pivotably mounted on said yielding means, saidengaging block being pivotable from a position in which it can engage anincoming car on the adjacent one of said incoming tracks to a positionin which said engaging block cannot engage incoming cars on the adjacentone of said incoming

1. In a unit carrier system in which a plurality of cars are driven overa trackway having merges therein, a merge assisting device forinterleaving on an outgoing track cars approaching a merge on aplurality of different incoming tracks without stopping said cars priorto the merge, said merge assisting device comprising: acontrolled-pathway, propelling device mounted adjacent to each of saidincoming tracks; at least one dog carried by each of saidcontrolled-pathway, propelling devices and positioned to engage anincoming car on the adjacent one of said incoming tracks and to remainin engagement with said car until it has reached an exit speed at leastequal to the speed of the fastest of said incoming cars times the numberof said incoming tracks; means for driving said controlled-pathway,propelling devices at said exit speed; and means for synchronizing saidcontrolled-pathway, propelling devices so that said cars reach saidmerge at intervals at least slightly in excess of the length of thelongest of said cars, whereby said cars may be interleaved on saidoutgoing track without danger of collision with one another.
 2. A mergeassisting device as claimed in claim 1 wherein at least one of saidcontrolled-pathway, propelling devices comprises: a chain and aplurality of sprockets for guiding said chain and imparting motionthereto.
 2. an engaging block positioned to engage an incoming car onthe adjacent one of said incoming tracks; and
 2. an engaging blockpositioned to engage an incoming car on the adjacent one of saidincoming tracks; and
 2. a spring co-axially disposed about said bolt;and
 2. a spring co-axially disposed about said bolt; and
 2. an engagingblocK positioned to engage one of said objects; and
 2. a springco-axially disposed about said bolt; and
 2. a spring co-axially disposedabout said bolt; and
 2. an engaging block positioned to engage anincoming car on the adjacent one of said incoming tracks; and 3.yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid cars on said engaging block.
 3. butting means mounted on said boltat an end thereof remote from said pull sleeve, said butting meansoperating to trap said spring between said pull sleeve and said buttingmeans, whereby said spring absorbs at least a part of the impact of saidcars on said engaging block.
 3. yielding means connecting said pullsleeve to said engaging block, whereby said yielding means absorbs atleast a part of the impact of said cars on said engaging block. 3.butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said cars on said engaging block. 3.butting means mounted on said bolt at an end thereof remote from saidpull sleeve, said butting means operating to trap said spring betweensaid pull sleeve and said butting means, whereby said spring absorbs atleast a part of the impact of said cars on said engaging block. 3.yielding means connecting said pull sleeve to said engaging block,whereby said yielding means absorbs at least a part of the impact ofsaid object on said engaging block.
 3. butting means mounted on saidbolt at an end thereof remote from said pull sleeve, said butting meansoperating to trap said spring between said pull sleeve and said buttingmeans, whereby said spring absorbs at least a part of the impact of saidobject on said engaging block.
 3. yielding means connecting said pullsleeve to said engaging block, whereby said yielding means absorbs atleast a part of the impact of said cars on said engaging block.
 3. Amerge assisting device as claimed in claim 2 wherein said sprockets aredriven in only one direction.
 4. A merge assisting device as claimed inclaim 2 wherein said sprockets are driven first in one direction, thenin the other, whereby said dog is recocked for successive cars.
 5. Amerge assisting device as claimed in claim 2 wherein said dog is carriedbetween two parallel chains.
 6. A merge assisting device as claimed inclaim 5 wherein said controlled-pathway, propelling device furthercomprises guide means for supporting said parallel chains and preventingdeviation thereof from their prescribed pathway during that portion oftheir prescribed pathway during which said dog is in position to engagesaid cars.
 7. A merge assisting device as claimed in claim 2 whereinsaid means for driving said controlled-pathway, propelling deviceincludes torsional springs which normally transmit torque to saidsprockets in the manner of a cylindrical shaft, but which absorb theimpact of said cars on said dog by curling or uncurling slightly.
 8. Amerge assisting device as claimed in claim 1 and further comprisingmeans for absorbing the impact of said cars on said dogs.
 9. A mergeassisting device as claimed in claim 1 wherein said controlled-pathway,propelling device extends from upstream of said merge at least to saidmerge.
 10. A merge assisting device as claimed in claim 1 wherein saiddog comprises:
 11. A merge assisting device as claimed in claim 10wherein said yielding means comprises a spring.
 12. A merge assistingdevice as claimed in claim 10 wherein said yielding means comprises: 13.A merge assisting device as claimed in claim 10 wherein said engagingblock is pivotably mounted on said yielding means, said engaging blockbeing pivotable from a position in which it can engage an incoming caron the adjacent one of said incoming tracks to a position in which saidengaging block cannot engage incoming cars on the adjacent one of saidincoming tracks.
 14. A merge assisting device as claimed in claim 1wherein said dog is pivotably mounted on said controlled-pathway,propelling device, said dog being pivotable from a position in which itcan engage an incoming car on the adjacent one of said incoming tracksto a position in which said engaging block cannot engage incoming carson the adjacent one of said incoming tracks.
 15. A dog adapted to bemounted on a controlled-pathway, propelling device and to impartmomentum to objects moving on a controlled path adjacent to saidcontrolled-pathway, propelling device, said dog comprising:
 16. A dog asclaimed in claim 15 wherein said yielding means comprises a spring. 17.A dog as claimed in claim 15 wherein said yielding means comprises: 18.A dog as claimed in claim 15 wherein said engaging block is pivotablymounted on said yielding means, said engaging block being pivotable froma position in which it can engage an incoming object to a position inwhich said engaging block cannot engage an incoming object.
 19. In aunit carrier system in which a plurality of cars are driven over atrackway having merges therein, a merge assisting device forinterleaving on an outgoing track cars approaching a merge on aplurality of different incoming tracks, said merge assisting devicecomprising: a. a controlled-pathway, propelling device mounted adjacentto each of said incoming tracks, the distance upstream of said merge towhich said controlled-pathway, reciprocating device extends beingsufficient so that an incoming car approaching said device just after adog (to be recited hereinafter) carried by said device has passed willbe brought into synchronization by the following dog before said car hasreached said merge; b. a plurality of dogs carried by at least one ofsaid controlled-pathway, propelling devices, said dogs being spaced by adistance slightly in excess of the longest of said cars times the numberof said incoming trackways and being positioned to engage an incomingcar on the adjacent one of said incoming tracks and to remain inengagement with said car until it has reached an exit speed at leastequal to the speed of the fastest of said incoming cars times the numberof said incoming tracks; c. at least one dog i. carried by each of saidcontrolled-pathway, propelling devices other than said at least one ofsaid controlled-pathway, propelling devices and ii. positioned to engagean incoming car on the adjacent one of said incoming tracks and toremain in engagement with said car until it has reached an exit speed atleast equal to the speed of the fastest of said incoming cars times thenumber of said incoming tracks; d. means for driving saidcontrolled-pathway, propelling devices at said exit speed; and e. meansfor synchronizing said controlled-pathway, propelling devices so thatsaid cars reach said merge at intervals at least slightly in excess ofthe length of the longest of said cars, whereby said cars may beinterleaved on said outgoing track without danger of collision with oneanother.
 20. A merge assisting device as claimed in claim 19 whereinsaid one of said controlled-pathway, propelling devices comprises: achain and a plurality of sprockets for guiding said chain and impartingmotion thereto.
 21. A merge assisting device as claimed in claim 20wherein said sprockets are driven in only one direction.
 22. A mergeassisting device as claimed in claim 20 wherein said sprockets aredriven first in one direction, then in the other, whereby said dog isrecocked for successive cars.
 23. A merge assisting device as claimed inclaim 20 wherein said dog is carried between two parallel chains.
 24. Amerge assisting device as claimed in claim 23 wherein saidcontrolled-pathway, propelling device further comprises guide means forsupporting said parallel chains and preventing deviation thereof fromtheir prEscribed pathway during that portion of their prescribed pathwayduring which said dog is in position to engage said cars.
 25. A mergeassisting device as claimed in claim 20 wherein said means for drivingsaid controlled-pathway, propelling device includes torsional springswhich normally transmit torque to said sprockets in the manner of acylindrical shaft, but which absorb the impact of said cars on said dogby curling or uncurling slightly.
 26. A merge assisting device asclaimed in claim 19 and further comprising means for absorbing theimpact of said cars on said dogs.
 27. A merge assisting device asclaimed in claim 19 wherein said one of said controlled-pathway,propelling device extends from upstream of said merge at least to saidmerge.
 28. A merge assisting device as claimed in claim 19 wherein saiddog comprises:
 29. A merge assisting device as claimed in claim 28wherein said yielding means comprises a spring.
 30. A merge assistingdevice as claimed in claim 28 wherein said yielding means comprises: 31.A merge assisting device as claimed in claim 28 wherein said engagingblock is pivotably mounted on said yielding means, said engaging blockbeing pivotable from a position in which it can engage an incoming caron the adjacent one of said incoming tracks to a position in which saidengaging block cannot engage incoming cars on the adjacent one of saidincoming tracks.
 32. A merge assisting device as claimed in claim 19wherein said dog is pivotably mounted on said controlled-pathway,propelling device, said dog being pivotable from a position in which itcan engage an incoming car on the adjacent one of said incoming tracksto a position in which said engaging block cannot engage incoming carson the adjacent one of said incoming tracks.
 33. In a unit carriersystem in which a plurality of cars are driven over a trackway havingmerges therein, a merge assisting device for interleaving on an outgoingtrack cars approaching a merge on a plurality of different incomingtracks, said merge assisting device comprising: a. a firstcontrolled-pathway, propelling device mounted adjacent to a first one ofsaid incoming tracks, the distance upstream of said merge to which saidfirst controlled-pathway, propelling device extends being sufficient sothat an incoming car approaching said first controlled-pathway,propelling device just after a dog (to be recited hereinafter) carriedby said device has passed will be brought into synchronization by saiddog on its next pass before said car has reached said merge, b. a singledog i. carried by said first controlled-pathway, propelling device andii. positioned to engage an incoming car on said first one of saidincoming tracks and to remain in engagement with said car until it hasreached an exit speed at least equal to the speed of the fastest of saidincoming cars times the number of said incoming track; c. an additionalcontrolled-pathway, propelling device mounted adjacent to the other oreach of the other additional incoming tracks; d. at least one dog i.carried by the other or each of the other additional incoming tracks andii. positioned to engagE an incoming car on the adjacent one of saidincoming tracks and to remain in engagement with said car until it hasreached an exit speed at least equal to the speed of the fastest of saidincoming cars times the number of said incoming tracks; e. means fordriving said controlled-pathway, propelling devices at said exit speed;and f. means for synchronizing said controlled-pathway, propellingdevices so that said cars reach said merge at intervals at leastslightly in excess of the length of the longest of said cars, wherebysaid cars may be interleaved on said outgoing track without danger ofcollision with one another.
 34. A merge assisting device as claimed inclaim 33 wherein said first controlled-pathway, propelling devicescomprises: a chain and a plurality of sprockets for guiding said chainand imparting motion thereto.
 35. A merge assisting device as claimed inclaim 34 wherein said sprockets are driven in only one direction.
 36. Amerge assisting device as claimed in claim 34 wherein said sprockets aredriven first in one direction, then in the other, whereby said singledog is recocked for successive cars.
 37. A merge assisting device asclaimed in claim 34 wherein said single dog is carried between twoparallel chains.
 38. A merge assisting device as claimed in claim 37wherein said first controlled-pathway, propelling device furthercomprises guide means for supporting said parallel chains and preventingdeviation thereof from their prescribed pathway during the portion oftheir prescribed pathway during which said dog is in position to engagesaid cars.
 39. A merge assisting device as claimed in claim 34 whereinsaid means for driving said first controlled-pathway, propelling deviceincludes torsional springs which normally transmit torque to saidsprockets in the manner of a cylindrical shaft, but which absorb theimpact of said cars on said single dog by curling or uncurling slightly.40. A merge assisting device as claimed in claim 33 and furthercomprising means for absorbing the impact of said cars on said singledog.
 41. A merge assisting device as claimed in claim 33 wherein saidfirst controlled-pathway, propelling device extends from upstream ofsaid merge at least to said merge.
 42. A merge assisting device asclaimed in claim 33 wherein said single dog comprises:
 43. A mergeassisting device as claimed in claim 42 wherein said yielding meanscomprises a spring.
 44. A merge assisting device as claimed in claim 42wherein said yielding means comprises:
 45. A merge assisting device asclaimed in claim 33 wherein said engaging block is pivotably mounted onsaid yielding means, said engaging block being pivotable from a positionin which it can engage an incoming car on the adjacent one of saidincoming tracks to a position in which said engaging block cannot engageincoming cars on the adjacent one of said incoming tracks.